Pressing direction sensor and input device using the same

ABSTRACT

A small and thin pressing direction sensor that can continually detect pressing directions in the angle range of 360 degrees is provided. This pressing direction sensor includes a ring-like resistive film pattern, a first electrode pattern, and a conductive member that electrically connects the resistive film pattern and the first electrode pattern when pressed. The voltage of the first electrode pattern represents the pressing direction. This pressing direction sensor may further include a second electrode pattern. A signal representing the pressing force can be obtained from the second electrode pattern when the pressed conductive member is brought into contact with the second electrode pattern.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a device for inputtingcoordinate information into an electronic apparatus, and moreparticularly, to a pressing direction sensor that can detect pressingdirections and pressing forces of a finger pointing on an operationunit.

[0003] 2. Description of the Related Art

[0004] Devices for inputting coordinate information into electronicdevices include pointing devices. Pointing devices have been widely usedas coordinate input means in personal computers and game machines. Inrecent years, these pointing devices are sometimes seen on small-sizeapparatuses such as portable telephones and PDAs, and are thereforeexpected to become smaller, thinner, lighter, and less costly.

[0005] For portable telephones and PDAs, onscreen pointing systems usedto be required to function only from side to side and up and down.However, as the amount of information to be handled on screen hasincreased, cursor operations that have been employed in personalcomputers are expected also in portable telephones and PDAs, so thatpointing operations in any direction can be performed at a controllablespeed.

[0006] Various types of coordinate input mechanisms have been developedas conventional pointing devices. Those coordinate input mechanismsinclude: a mechanism that employs a magnet to be inclined by fingerpointing and a plurality of electromagnetic conversion devices; and amechanism that employs an optical detection system. However, any ofthose types of mechanisms structurally requires a certain thickness, andof course has limitations on portable devices to which it can bemounted. There are flat input devices such as touch pads, but a flatinput device requires a certain area because of the operation method ofstroking the pad surface with a finger.

[0007] In general, pointing devices that employ resistive film patternsand conductive pressure-sensitive rubber can achieve decreases in sizeand thickness. Such pointing devices have been developed and disclosedin Japanese Unexamined Patent Publication Nos. 6-139880, 7-320597,11-203036, 2001-210191, and 2001-311671.

SUMMARY OF THE INVENTION

[0008] It is therefore an object of the present invention to provide asmall and thin pressing direction sensor that can continually detectpressing directions in the angle range of 360 degrees, having adifferent structure from the prior arts disclosed in the above describedpatent publications.

[0009] Another object of the present invention is to provide a pressingdirection sensor that can detect pressing forces as well as pressingdirections.

[0010] Yet another object of the present invention is to provide anelectronic device that employs the above pressing direction sensor.

[0011] The above objects of the present invention are achieved by apressing direction sensor including: a ring-like resistive film pattern;a first electrode pattern; and a conductive member that is electricallyconnected to the resistive film pattern and the first electrode patternwhen pressed, the potential of the resistive film pattern at the pointof contact of the conductive member with the resistive film patternbeing outputted from the first electrode pattern, so as to detect apressing direction.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Other objects, features and advantages of the present inventionwill become more apparent from the following detailed description whenread in conjunction with the accompanying drawings, in which:

[0013]FIGS. 1A and 1B are sectional views of a pressing direction sensoraccording to a first embodiment of the present invention;

[0014]FIG. 2 illustrates a pattern formed on the printed wiring board ofthe pressing direction sensor shown in FIGS. 1A and 1B;

[0015]FIG. 3 is a circuit diagram illustrating the detection circuit ofthe pressing direction sensor shown in FIGS. 1A and 1B;

[0016]FIGS. 4A and 4B are sectional views illustrating a pressingdirection sensor according to a second embodiment of the presentinvention;

[0017]FIG. 5 illustrates a pattern formed on the printed wiring board ofthe pressing direction sensor shown in FIGS. 4A and 4B;

[0018]FIGS. 6A and 6B are circuit diagrams illustrating the detectioncircuit of the pressing direction sensor shown in FIGS. 4A and 4B;

[0019]FIG. 7 is a sectional view illustrating a pressing directionsensor according to a third embodiment of the present invention;

[0020]FIG. 8 illustrates a pattern formed on the printed wiring board ofthe pressing direction sensor shown in FIG. 7;

[0021]FIG. 9 illustrates a conductive pressure-sensitive rubber sheetemployed in the pressing direction sensor shown in FIG. 7;

[0022]FIGS. 10A and 10B are circuit diagrams illustrating the detectioncircuit of the pressing direction sensor shown in FIG. 7;

[0023]FIG. 11 illustrates a pattern formed in a pressing directionsensor according to a fourth embodiment of the present invention;

[0024]FIGS. 12A and 12B illustrate a pressing direction sensor accordingto a fifth embodiment of the present invention;

[0025]FIGS. 13A and 13B illustrate a pressing direction sensor accordingto a sixth embodiment of the present invention;

[0026]FIG. 14 illustrates a pattern formed in a pressing directionsensor according to a seventh embodiment of the present invention;

[0027]FIG. 15 illustrates the detection circuit of the pressingdirection sensor according to the seventh embodiment of the presentinvention;

[0028]FIG. 16 is a flowchart showing the operation sequence of thedetection circuit shown in FIG. 15;

[0029]FIG. 17 is a graph illustrating the relationship between thepressing force and the resistance value of a pressing member made ofconductive pressure-sensitive rubber;

[0030]FIGS. 18A and 18B are sectional views illustrating a pressingdirection sensor according to an eighth embodiment of the presentinvention;

[0031]FIG. 19 illustrates a pattern formed on the printed wiring boardof the pressing direction sensor shown in FIGS. 18A and 18B;

[0032]FIG. 20 illustrates the detection circuit of the pressingdirection sensor according to the eighth embodiment of the presentinvention;

[0033]FIG. 21 illustrates a pattern formed in a pressing directionsensor according to a ninth embodiment of the present invention;

[0034]FIG. 22 is a sectional view of a pressing direction sensoraccording to a tenth embodiment of the present invention;

[0035]FIG. 23 illustrates a pattern formed on the printed wiring boardof the pressing direction sensor shown in FIG. 22;

[0036]FIG. 24 illustrates a circuit formed between the electrodepatterns shown in FIG. 23;

[0037]FIG. 25 is a sectional view of a pressing direction sensoraccording to an eleventh embodiment of the present invention;

[0038]FIG. 26 illustrates a pattern formed on the printed wiring boardof the pressing direction sensor shown in FIG. 25;

[0039]FIG. 27 illustrates the detection circuit of the pressingdirection sensor according to the eleventh embodiment of the presentinvention;

[0040]FIG. 28 is a sectional view of a pressing direction sensoraccording to a twelfth embodiment of the present invention;

[0041]FIG. 29 illustrates a membrane sheet employed in the pressingdirection sensor shown in FIG. 28;

[0042]FIG. 30 is a perspective view illustrating the outlook of thepressing direction sensor shown in FIG. 28;

[0043]FIG. 31 is a sectional view of a pressing direction sensoraccording to a thirteenth embodiment of the present invention;

[0044]FIG. 32 is a graph illustrating the relationship between thepressed length and the pressing force of a pressing member;

[0045]FIG. 33 illustrates an example of an electronic device having apressing direction sensor according to the present invention on aprinted wiring board;

[0046]FIG. 34 illustrates another example of an electronic device; and

[0047]FIG. 35 is a block diagram illustrating an example of the innerstructure of an electronic device.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0048] The following is a description of embodiment of the presentinvention, with reference to the accompanying drawings.

[0049] (First Embodiment)

[0050]FIGS. 1A and 1B are sectional views of a pressing direction sensoraccording to the first embodiment of the present invention. FIG. 1Aillustrates the stationary state of the sensor, and FIG. 1B illustratesthe operation state of the sensor.

[0051] The pressing direction sensor shown in FIGS. 1A and 1B includes aprinted wiring board 10 and a pressing member. Patterns shown in FIG. 2are formed on the surface of the printed wiring board 10. A pattern 13is a round electrode pattern, and a pattern 14 is a ring-shapedresistive film pattern surrounding the pattern 13. The printed wiringboard is formed of an insulating material, and has the patterns 13 and14 printed thereon. The resistive film 14 is a resistive carbon filmhaving linear characteristics, for example. The center of the electrodepattern 13 corresponds to the center of the resistive film pattern 14.In other words, the electrode pattern 13 and the resistive film pattern14 are concentrically arranged. The resistive film pattern 14 has aring-like shape, with a part of the ring being notched. As a result, theresistive film pattern 14 has opening ends facing each other. Extractionelectrodes 15 and 16 are formed at the opening ends. These extractionelectrodes 15 and 16 extend to the bottom surface of the printed wiringboard 10 via through holes 17 and 18 formed in the printed wiring board10. A voltage Vcc is applied to the extraction electrode 15, and theextraction electro 16 is grounded. The electrode pattern 13 extends tothe bottom surface of the printed wiring board 10 via a through hole 19formed in the printed wiring board 10.

[0052] The pressing member 11 is placed on the printed wiring board 10,and the bottom surface of the pressing member 11 faces the electrodepattern 13 and the resistive film pattern 14. This bottom surface of thepressing member 11 is round, and gently sloped toward the center. Asshown in FIG. 2, the bottom surface of the pressing member 11 is curved,and a conductive part 12 is formed on the curved portion. Of the curvedportion, protrusions that protrude downward are located in the positionscorresponding to the electrode pattern 13 and the resistive film pattern14. In the stationary state shown in FIG. 1A, only the middle protrusionis in contact with the electrode pattern 13. The conductive part 12 maybe a metal film. The pressing member 11 may be formed by resin. Thepressing member 11 and the conductive part 12 may be replaced with apressing member made of conductive rubber.

[0053]FIG. 3 is a circuit diagram illustrating the detection circuit ofthe pressing direction sensor shown in FIGS. 1A and 1B. The voltage Vccis applied to one end of the resistive film pattern 14 via theextraction electrode 15, while the other end of the resistive filmpattern 14 is grounded via the extraction electrode 16. The resistors R1and R2 shown in FIG. 3 forms a voltage division circuit. In thestationary state, the electrode pattern 13 is not connected to theresistive film pattern 14. As shown in FIG. 1B, when the pressing member11 is pressed in a certain direction, the conductive part 12 is broughtinto contact with the resistive film pattern 14. The arrow 20 in FIG. 2indicates that the pressing member 11 is pressed so that the conductivepart 12 is brought into contact with the resistive film pattern 14 atthe position pointed out with the arrow 20. Thus, the electrode pattern13 is electrically connected to the resistive film pattern 14 via theconductive part 12. As a result, a detection voltage Vout correspondingto the grounding position (or a potential corresponding to thegrounding) appears on the electrode pattern 13. The closer the contactposition is to the voltage Vcc, i.e., the extraction electrode 15, thehigher the detection voltage Vout is. The size of the detection voltageVout represents the contact position, i.e., the pressing direction.

[0054] In this manner, the pressing direction sensor according to thefirst embodiment of the present invention can detect the pressingdirection in the angle range of 360 degrees. Moreover, this pressingdirection sensor is made up of a small number of components, and issmaller and thinner than conventional sensors.

[0055] (Second Embodiment)

[0056]FIGS. 4A and 4B are sectional view showing a pressing directionsensor according to a second embodiment of the present invention. FIG.4A illustrates the stationary state of the pressing direction sensor,and FIG. 4B illustrates a pressed state thereof. In FIGS. 4A and 4B, thesame components as descried in the first embodiment are denoted by likereference numerals. Further, FIG. 5 shows a pattern formed on thesurface of the printed wiring board 10, and FIGS. 6A and 6B show thedetection circuit. The pressing direction sensor according to the secondembodiment is characterized by being able to detect pressing force aswell as the pressing direction.

[0057] As shown in FIGS. 4A, 4B, and 5, the pressing direction sensor ofthis embodiment further includes a ring-like electrode pattern 21.Hereinafter, the above described electrode pattern 13 will be referredto as a first electrode pattern, and the electrode pattern 21 a secondelectrode pattern. The second electrode pattern 21 is situated outsidethe first electrode pattern 13, and inside the resistive film pattern14. In other words, the second electrode pattern 21 is situated betweenthe first electrode pattern and the resistive film pattern 14. Thesecond electrode pattern 21 extends to the bottom surface of the printedwiring board 10 via a through hole formed in the printed wiring board10.

[0058] A pressing member (also referred to as an operation unit) 22 ismade of a conductive pressure-sensitive material, such as a conductivepressure-sensitive rubber, which has elasticity and a resistance valuevariable with pressures applied thereto. In general, a conductivepressure-sensitive rubber is compressed by a large pressure and reducesthe resistance accordingly. The pressure member 22 is a round flatmember. The surface of the pressure member 22 is gently sloped towardthe center. The pressure member 22 is secured onto the printed wiringboard 10 with a fixing member 23, which penetrates through the printedwiring board 10. The pressing member 22 has three protruding portions insection, and these protruding portions are in contact with the surfaceof the printed wiring board 10. The center protruding portion has amountain-like shape, and a ring-like protruding portion is formed aroundthe center protruding portion. This middle protruding portion is alwaysin contact with the electrode pattern 13, and the other protrudingportion is separate from the second electrode pattern 21 and theresistive film pattern 14 in the stationary state. As shown in FIG. 4B,when the pressing member 22 is pressed in a direction, the outerprotruding portion is brought into contact with the resistive filmpattern 14 and the electrode pattern 12. At this point, a voltage isapplied to the second electrode pattern 21 via the voltage divisioncircuit, so that a current can flow to the ground through the voltagedivision circuit and the pressing member 22. Thus, a detection voltageVout2 corresponding to the size of the current appears on the electrodepattern 21.

[0059]FIGS. 6A and 6B illustrate the detection circuit of the pressingdirection sensor according to the second embodiment of the presentinvention. FIG. 6A shows a circuit for detecting the pressing direction,which has the same circuit structure as the circuit structure shown inFIG. 3, except that the detection voltage Vout is detected from theelectrode pattern 21. FIG. 6B shows a circuit for detecting a pressingforce. The circuit shown in FIG. 6A is substantially the same as thecircuit shown in FIG. 3, and therefore explanation for it is omittedherein. In FIG. 6, the pressing member 22 is shown as a variableresistor, being a conductive pressure-sensitive member that has aresistance value variable with pressures applied thereto. A switch thatis connected in series with the variable resistor implies that thepressing member 22 is electrically connected to the second electrodepattern 21 when pressed. A voltage Vcc is applied to the secondelectrode pattern 21 via a resistor R3 for voltage division. Theconductive pressing member 22 is grounded via the electrode pattern 13,for example. Since the resistance value of the pressing member 22 varieswith pressures, the potential of the electrode pattern 21, i.e., thedetection voltage Vout2 varies with the pressures. Accordingly, apressure applied to the pressing member 22 can be detected from thedetection voltage Vout2.

[0060] In the above manner, the pressing direction sensor according tothe second embodiment of the present invention switches the connectionsto the terminals so as to obtain a pressing direction and the detectionvoltage corresponding to the pressing force in the circuit structuresshown in FIGS. 6A and 6B. By doing so, this pressing direction sensorcan detect pressing directions in the angle range of 360 degrees.Furthermore, this pressing direction sensor has a small number ofcomponents, and is smaller and thinner than the conventional sensors. Ifthis pressing direction sensor is used as a pointer device for apersonal computer, pressing force can be varied with the moving speed ofthe cursor.

[0061] (Third Embodiment)

[0062]FIG. 7 is a sectional view of a pressing direction sensoraccording to a third embodiment of the present invention. FIG. 8 shows apattern formed on the surface of the printed wiring board 10 shown inFIG. 7. This pressing direction sensor according to the third embodimenthas a switch ON/OFF function, as well as the pressing directiondetecting function and the pressing force detecting function.

[0063] As shown in FIG. 8, two ring-like electrode patterns 31 and 33are formed inside the resistive film pattern 14. The resistive filmpattern 14 and the electrode patterns 31 and 33 are concentricallyarranged. The electrode pattern 31 is equivalent to the second electrodepattern 21 of the second embodiment, and the electrode pattern 33 isequivalent to the first electrode pattern 13 of the second embodiment.One end of an extended line from the electrode pattern 31 extends to thebottom surface of the printed wiring board 10 via a through hole formedin the printed wiring board 10, and is connected to an extractionelectrode 44 formed on the upper surface of the printed wiring board 10via the through hole. Likewise, one end of an extended line from theelectrode pattern 33 extends to the bottom surface of the printed wiringboard 10 via a through hole formed in the printed wiring board 10, andis connected to an extraction electrode 41 formed on the upper surfaceof the printed wiring board 10 via the through hole. The extractionelectrodes 41 and 44 may be formed on the bottom surface of the printedwiring board 10. Further, the two facing ends of the resistive filmpattern 14 are respectively connected to extraction electrodes 42 and 43formed on the upper surface of the printed wiring board 10. Theextraction electrodes 42 and 43 may be formed on the bottom surface ofthe printed wiring board 10.

[0064] The center of the pattern shown in FIG. 8 has a tactile switch 34placed thereon. The tactile switch 34 consists of an electrode pattern34 a formed on the printed wiring board 10, and an elastic member 34 bmade of an arch-like conductive member. The elastic member 34 b isseparate from the electrode pattern 34 a in the stationary state. When avertical force is applied to the printed wiring board 10, the elasticmember 34 b is deformed and is electrically connected to the electrodepattern 34 a. The electrode pattern 34 a is connected to an extractionelectrode formed on the bottom surface of the printed wiring board 10via a through hole formed in the printed wiring board 10. Likewise, theelastic member 34 b is connected to an extraction electrode formed onthe bottom surface of the printed wiring board 10 via a through holeformed in the printed wiring board 10.

[0065] As shown in FIG. 7, two ring-like spacers 36 and 37 are providedon the printed wiring board 10. The spacer 36 is arranged outside theresistive film pattern 14, and the spacer 37 is arranged inside theelectrode pattern 33. The spacer 37 is located on the elastic member 34b. Further, a ring-like conductive pressure-sensitive rubber sheet 35shown in FIG. 9 is arranged on the two spacers 36 and 37. In thestationary state, the conductive pressure-sensitive rubber sheet 35 isseparate from the resistive film pattern 14 and the electrode patterns31 and 33. In this arrangement, the spacers 36 and 37 serves to maintaina predetermined distance between the conductive pressure-sensitiverubber sheet 35 and the patterns on the printed wiring board 10 in thestationary state.

[0066] As shown in FIG. 7, a pressing member (or an operation unit) 32is further provided. The pressing member 32 is made of an insulatingmaterial such as resin, and is placed on the printed wiring board 10.The pressing member 32 has a flange portion that is in contact with theprinted wiring board 10, and the flange portion is engaged with aholding member 38. The holding member 38 has a screw hole, and issecured to the printed wiring board 10 with a screw 39. Although notshown, another holding member is provided in the left half of FIG. 7.The pressing member 32 has an outward protruding portion and two inward(toward the printed wiring board 10) protruding portions. The centerinward protruding portion is an angled protrusion that is in contactwith the elastic member 34 b in the stationary state. The other inwardprotruding portion has a ring-like shape and is located outside theangled inner protruding portion. This outer inward protruding portion isin contact with the conductive pressure-sensitive rubber sheet 35 in thestationary state.

[0067]FIGS. 10A and 10B illustrate the detection circuit of the pressingdirection sensor according to this embodiment. FIG. 10A shows thecircuit for detecting pressing direction. FIG. 10B shows the circuit fordetecting pressing forces. The circuit shown in FIG. 10A is the same asthe circuits shown in FIGS. 3 and 6A. In FIG. 10a, a voltage Vcc isapplied to the extraction electrode 42 via a resistor R1 for voltagedivision. The extraction electrode 43 is grounded via a resistor R2 forvoltage division. When the pressing member 32 is pressed in onedirection, the conductive pressure-sensitive rubber sheet 35 is broughtinto contact with the resistive film pattern 14 and the electrodepatterns 31 and 33. As a result, a detection voltage Vout1 correspondingto the contact position appears on the extraction electrode 41. In FIG.10B, as the conductive pressure-sensitive rubber sheet 35 is broughtinto contact with the electrode pattern 31, a current flows through theconductive pressure-sensitive rubber sheet 35 via a resistor R3 forvoltage division. As a result, a detection voltage Vout2 that isdetermined by the resistance value corresponding to the pressing forceof the conductive pressure-sensitive rubber sheet 35 appears on theextraction electrode 44.

[0068] If the pressing member 32 is pressed vertically downward, theconductive elastic member 34 b is brought into contact with theelectrode pattern 34 a, and the tactile switch 34 is turned on.

[0069] As described above, the pressing direction sensor according tothe third embodiment of the present invention can detect pressingforces, as well as pressing directions in the angle range of 360degrees. This pressing direction sensor can further detect ON/OFF statescorresponding to vertical-direction operations. Moreover, this pressingdirection sensor has a small number of components, and is thereforesmaller and thinner than the conventional sensors.

[0070] Alternatively, the pressing member 32 and the conductivepressure-sensitive rubber sheet 35 may be integrally formed, and theentire pressing member 32 may be molded out of conductivepressure-sensitive rubber. In this case, the surface of the conductivepressure-sensitive rubber facing the printed wiring board 10 can beseparated from the printed wiring board 10, and thereby the spacer 36and 37 become unnecessary. Accordingly, the number of components can befurther reduced, and a simpler structure can be realized.

[0071] (Fourth Embodiment)

[0072]FIG. 11 illustrates the pattern of a pressing direction sensoraccording to a fourth embodiment of the present invention. In thisfigure, the same components as shown in FIG. 8 are denoted by the samereference numerals as in FIG. 8. The fourth embodiment is a modificationof the third embodiment, and aims to further increase the accuracy inthe pressing direction detecting operation.

[0073] As shown in FIG. 11, the resistive film pattern 14 has extractionelectrodes 46, 47, and 48 at uniform intervals (every 90 degrees), aswell as the extraction electrodes 42 and 43. When the voltage Vcc isapplied to the extraction electrodes 42 and 43, a voltage correspondingto the distance from the opening end to which the extraction electrode42 appears on the extraction electrodes 46, 47, and 48. If the potentialdifference between the extraction electrodes 47 and 48 is V, forinstance, each voltage change is V/90. After the detection voltage Vout1appears on the electrode pattern 33 as a result of the pressing of thepressing member 32 shown in FIG. 7 and the contact between theconductive pressure-sensitive rubber sheet 35 and the resistive filmpattern 14, the voltages of the extraction electrodes 47 and 48 arecompared so as to determine the pressing angle.

[0074] If the difference between the pressing angle determined in thismanner and the pressing angle determined directly from the detectionvoltage Vout1 is larger than a predetermined value, an error signal maybe outputted. Alternatively, the pressing angle determined throughcomparison among the extraction electrodes 46-48 may be outputted,instead of the pressing angle determined directly from the detectionvoltage Vout1.

[0075] As described above, the pressing direction sensor according tothe fourth embodiment of the present invention can perform more accuratepressing direction detecting operations. The accuracy in pressingdirection detection can also be increased by providing the extractionelectrodes 46-48 shown in FIG. 11 to the resistive film pattern 14 shownin FIG. 5.

[0076] (Fifth Embodiment)

[0077]FIGS. 12A and 12B illustrate a pressing direction sensor accordingto a fifth embodiment of the present invention. FIG. 12A is a sectionalview of the pressing direction sensor, and FIG. 12B shows a patternformed on a membrane sheet. It should be noted that emphasis is put onthe vertical direction in FIG. 12A, for ease of understanding. The fifthembodiment aims to detect pressing directions, and has the samedetection principles as the first embodiment. One of the characteristicsof the fifth embodiment is the formation of a pattern on a membranesheet.

[0078] An operation unit 52 is provided on a support panel 51, and aconductive pressure-sensitive rubber 55 and rectangular membrane sheets53 and 57 that sandwich the conductive pressure-sensitive rubber 55 arearranged between the bottom surface of the operation unit 52 and thesupport panel 51. The membrane sheet 57 is a PET film 100 μm thick, forexample, and is fixed on the support panel 51 with an adhesive agent orthe like. The exploded view of the membrane sheets 53 and 57 is shown inFIG. 12B. As shown in this figure, the membrane sheets 53 and 57 areformed by folding one membrane sheet at a folding portion 58. Themembrane sheets 53 and 57 may be two separate sheets, instead of theintegrally formed sheets shown in FIG. 12B. A round-shaped electrodepattern 54 is formed on the membrane sheet 53. On the other hand, aring-like resistive film pattern 56 is formed on the membrane sheet 57.The resistive film pattern 56 has a notch, and extraction electrodes 59and 60 are connected to the facing ends of the notch. The extractionelectrodes 59 and 60, as well as an extraction electrode 61 connected tothe electrode pattern 54, extend onto a rectangular protrusion of themembrane sheet 57. At this protrusion, electric connection with theoutside is formed. As the membrane sheet 53 is placed over the membranesheet 57 by the folding at the folding portion 58, the electrode pattern54 and the resistive film pattern 56 are concentrically arranged. Adisk-like conductive pressure-sensitive rubber 55 is interposed betweenthe membrane sheets 53 and 57.

[0079] The resistive film pattern 56 can be formed by printing withcarbon paste. The electrode pattern 54 and the extraction electrodes59-61 can be formed by printing with Ag paste.

[0080] The detection circuit of the fifth embodiment has the samestructure as the detection circuit shown in FIG. 3. A voltage Vcc and aground voltage are applied to the extraction electrodes 59 and 60,respectively. When the pressing direction sensor is in the stationarystate, the resistance value of the conductive pressure-sensitive rubber55 is high. Therefore, no detection voltage appears on the extractionelectrode 61 of the electrode pattern 54. On the other hand, when theconductive pressure-sensitive rubber 55 is pressed in one direction, theresistance value of the pressed point decreases, and a detection voltageappears on the extraction electrode 61. This detection voltage varieswith points on the resistive film pattern 56 corresponding to pressedpoints of the conductive pressure-sensitive rubber 55. Accordingly, thedetection voltage reflects the pressing direction.

[0081] As described above, in accordance with the fifth embodiment,there is no need to form a through hole in the support panel 51, andtherefore the manufacturing of the pressing direction sensor can befacilitated. Also, since there is no need to form a pattern on a printedwiring board, various applications are possible.

[0082] (Sixth Embodiment)

[0083]FIGS. 13A and 13B illustrate a pressing direction sensor accordingto a sixth embodiment of the present invention. FIG. 13A is a sectionalview of the pressing direction sensor, and FIG. 13B shows a patternformed on a membrane sheet. It should be noted that emphasis is put onthe vertical direction in FIG. 13A, for ease of understanding. The sixthembodiment aims to detect pressing directions, and one of thecharacteristics of the sixth embodiment is the formation of a pattern ona membrane sheet.

[0084] An operation unit 62 is provided on a support panel 51, and aconductive pressure-sensitive rubber 65 and round-shaped membrane sheets63 and 67 that sandwich the conductive pressure-sensitive rubber 65 arearranged between the bottom surface of the operation unit 62 and thesupport panel 51. The membrane sheet 67 is fixed on the support panel 51with an adhesive agent or the like. The exploded view of the membranesheets 63 and 67 is shown in FIG. 13B. As shown in this figure, themembrane sheets 63 and 67 are formed by folding one membrane sheet at afolding portion 68. The membrane sheets 63 and 67 may be two separatesheets, instead of the integrally formed sheets shown in FIG. 13B. Aring-like resistive film pattern 66 is formed on the membrane sheet 67,and a ring-like electrode pattern 69 is formed and arrangedconcentrically inside the resistive film pattern 66. Also, a ring-likeresistive film pattern 64 is formed on the membrane sheet 63. Theresistive film pattern 66 has a notch, and extraction electrodes 59 and60 are connected to the facing ends of the notch. Also, an extractionelectrode 71 is connected to the electrode pattern 69. The extractionelectrodes 59, 60, and 71, as well as an extraction electrode 61connected to the electrode pattern 64, extend onto a rectangularprotrusion of the membrane sheet 67. At this protrusion, electricconnection with the outside is formed. As the membrane sheet 63 isplaced over the membrane sheet 67 by the folding at the folding portion68, the electrode pattern 64, the resistive film pattern 66, and theelectrode pattern 69 are concentrically arranged.

[0085] The ring-like conductive pressure-sensitive rubber 65 isinterposed between the membrane sheets 63 and 67. A hole formed at thecenter of the conductive pressure-sensitive rubber 65 is positionedconcentrically with holes 72 a and 72 b formed at the centers of themembrane sheets 63 and 67. A support member 70 protrudingperpendicularly from the support panel 51 is inserted into these holes,so that the conductive pressure-sensitive rubber 65 and the membranesheets 63 and 67 can be precisely positioned on the support panel 51.

[0086] The detection of pressing directions is performed in the samemanner as in the fifth embodiment. The detection of a pressing force isperformed by detecting the potential difference between the extractionelectrodes 61 and 71. A voltage is applied to the electrode pattern 64via a resistor R3 for voltage division, and the electrode pattern 69 isgrounded, or vise versa. As the operation unit 62 is pressed in onedirection, the resistance value of the conductive pressure-sensitiverubber 65 at the pressed point decreases, and a current flows throughthe conductive pressure-sensitive rubber 65. As a result, the potentialof the electrode pattern 64 (or the extraction electrode 61) decreasesaccordingly. The potential of the electrode pattern 64 depends on theresistance value of the conductive pressure-sensitive rubber 65 betweenthe electrode patterns 64 and 69, and reflects the pressing force.

[0087] As described above, in accordance with the sixth embodiment,there is no need to form a through hole in the support panel 51, andtherefore the manufacturing of the pressing direction sensor can befacilitated. Also, since there is no need to form a pattern on a printedwiring board, various applications are possible.

[0088] (Seventh Embodiment)

[0089]FIG. 14 shows a pattern of a pressing direction sensor accordingto a seventh embodiment of the present invention. In FIG. 14, the samecomponents as shown in FIG. 5 are denoted by the same reference numeralsas in FIG. 5. The seventh embodiment aims to further increase thepressing direction detecting accuracy of the second embodiment. Inaccordance with the second embodiment, the pressing direction of thenotch portion (the opening) of the resistive film pattern 14 cannot bedetected accurately. The seventh embodiment is to solve this problem,and is characterized by having a center switch function. This centerswitch function is turned on when the pressing member 22 is pressedvertically downward.

[0090] An electrode pattern 26 is provided between the facing openingends of the resistive film pattern 14. An extraction electrode 27 isconnected to the electrode pattern 26. When the pressing member 22 shownin FIGS. 4A and 4B presses the notch portion of the resistive filmpattern 14 (i.e., the electrode pattern 26), the electrode pattern 21 ispressed as well. As a result, the electrode patterns 21 and 26 becomeconductive to each other via the pressing member made of conductivepressure-sensitive rubber of the like. By sensing this, the pressingdirection that corresponds to the notch portion of the resistive filmpattern 14 can be detected.

[0091]FIG. 15 shows the detection circuit according to this embodiment.The detection circuit is designed to prevent unnecessary currentconsumption, as well as to detect pressing directions. To avoidexcessive current consumption, the detection circuit is provided withswitches SW1 through SW4 and a center switch ON/OFF detecting function.In FIG. 15, the long rectangles represent a voltage division circuit,and the series circuits of variable resistors and switches indicated bythe broken lines represent the pressing member 22 shown in FIGS. 4A and4B. Vout 1 represents a voltage that appears on an extraction electrode29 connected to the electrode pattern 13 and reflects a pressingdirection. Vout 2 represents a voltage that appears on an extractionelectrode 28 connected to the electrode pattern 21. In the circuitstructure shown in FIG. 15, the extraction electrodes 28 and 29 areconnected to a common terminal. A voltage Vm appears on the extractionelectrode 27 connected to the electrode pattern 26. This voltage Vmappears when a pressed point on the pressing member 22 corresponds tothe notch portion of the resistive film pattern 14, i.e., when the pointover the electrode pattern 26 is pressed.

[0092]FIG. 16 is a flowchart showing the operation sequence of thedetection circuit shown in FIG. 15. In the initial state, the switchesSW1 and SW3 are ON, and the switches SW2 and SW4 are OFF. In step S11,an output voltage Vout is recognized. As can be seen from the circuitdiagram of FIG. 15, in the stationary state, the resistance of thepressing member 22 made of conductive pressure-sensitive rubber is high,and the switches shown within the broken-line blocks in FIG. 15 are OFF.Accordingly, no paths exist for a current flowing from a voltage Vcctoward the ground. When the pressing member 22 is pressed, the switchesshown within the broken-line blocks are turned ON, and a current paththat includes the switches SW1 and SW3 is formed.

[0093] In a case where the pressing member 22 is pressed verticallydownward, the relationship between the pressing force and the resistancevalue of the pressing member 22 made of conductive pressure-sensitiverubber becomes as shown in the graph of FIG. 17. In this graph, a curveA represents the characteristics of a case where the pressing member 22is pressed in any one direction, and a curve B represents thecharacteristics of a case where the pressing member 22 is pressedvertically downward. As can be seen from the graph, even if the pressingforces applied are the same, the pressing member 22 has a smallerresistance value when pressed vertically downward.

[0094] When the pressing member 22 is pressed vertically downward, theelectrode patterns 13 and 21 become conductive to each other via thepressing member 22 that has conductivity over the entire circumference.At this point, the output voltage Vout has a value in accordance withthe characteristics curve B of FIG. 17. This means that the outputvoltage Vout is a relatively high voltage. If an output voltagecorresponding to a resistance value that can be used for distinguishingthe curves A and B is set as a threshold voltage, an output voltage Voutof the curve A can be distinguished from an output voltage Vout of thecurve B. If the output voltage Vout is higher than the threshold voltage(this output voltage will be hereinafter referred to as Vn) in step S12,it is determined in step S13 that the center switch has been turned ON.If the output voltage Vout is not higher than the threshold voltage, thecenter switch is determined to be OFF, and the operation moves on tostep S14.

[0095] In step S14, a pressing force (a pressing strength) correspondingto the output voltage Vout is determined. In this case, the outputvoltage Vout is equivalent to the output voltage Vout2 shown in FIG. 14.In step S15, the switches SW1 and SW3 are turned OFF, and the switchesSW2 and SW4 are turned ON instead. By doing so, a path running from thevoltage Vcc to the resistive film pattern 14 and the switch SW4, and apath running from the voltage Vcc to the pressing member 22 and theswitch SW4, are formed. In step S16, it is determined whether thevoltage Vm of the electrode pattern 26 has appeared on the extractionelectrode 27. If the voltage Vm is detected, the operation moves on tostep S17, in which the pressing direction θ is of 0 degree. The pointcorresponding to the pressing direction θ of 0 degree is located on theelectrode pattern 26. If the pressing direction θ is not of 0 degree,the operation moves on to step S18, in which the value of the detectionvoltage Vout (corresponding to the output voltage Vout1 shown in FIG.14) is obtained. In step S19, the pressing direction corresponding tothe detection voltage Vout is detected. Finally, in step S20, theswitches SW1 through SW4 are put back into the initial state, and theoperation comes to an end.

[0096] As described above, the pressing direction sensor according tothe seventh embodiment of the present invention is provided with thefunction to detect the direction θ of 0 degree and the center switchfunction, as well as the functions to detect pressing directions andpressing forces. Furthermore, the pressing direction detection isperformed, with the switches SW2 and SW4 being turned ON only after theoutput voltage Vout is recognized in step S11. Accordingly, thedetection circuit of FIG. 15 does not consume current while the pressingmember 22 is not being operated. In this manner, a small and thinpressing direction sensor that has a very high accuracy in detectingpressing directions, and is provided with the center switch function soas to save power consumption, can be realized in accordance with theseventh embodiment.

[0097] This embodiment is not limited to the combination with thepressing member 22, but may be combined with any of the embodiments thathave already been described or will be described later. For example,this embodiment can be combined with the pressing member 11 having theconductive part 12 of the first embodiment. Also, the center switchfunction is applicable to any other embodiment (except for theembodiment employing a tactile switch).

[0098] The operation shown in the flowchart of FIG. 16 is performed by acentral processing unit that will be described later and shown in FIG.35.

[0099] (Eighth Embodiment)

[0100]FIGS. 18A and 18B are sectional views illustrating a pressingdirection sensor according to an eighth embodiment of the presentinvention. FIG. 18A shows the stationary state of the pressing directionsensor, and FIG. 18B shows an operation state of the pressing directionsensor. In these figures, the same components as in the foregoingembodiments are denoted by the same reference numerals as in theforegoing embodiments. FIG. 19 shows a pattern formed on the surface ofthe printed wiring board 10.

[0101] The pressing direction sensor according to this embodimentincludes a resistive film pattern 74 of a complete ring shape. Fourextraction electrodes 74 ₁ through 74 ₄ are connected to the resistivefilm pattern 74 at intervals of 90 degrees. These extraction electrodes74 ₁ through 74 ₄ extend onto the bottom surface of the printed wiringvia a through hole formed in the printed wiring board 10. The extractionelectrodes 74 ₁ and 74 ₃ facing each other, and the extractionelectrodes 74 ₂ and 74 ₄ facing each other, form two pairs of extractionelectrodes. An electrode pattern 73 is concentrically formed inside theresistive film pattern 74. The electrode pattern 73 has an extractionelectrode 73 ₁ that extends onto the bottom surface of the printedwiring board 10 via a through hole formed in the printed wiring board10.

[0102]FIG. 20 shows a circuit diagram of the pressing direction sensorof this embodiment.

[0103] In the stationary state shown in FIG. 18A, the pressing member 22made of conductive pressure-sensitive rubber or the like is in contactwith the electrode pattern 73, but not with the resistive film pattern74. As shown in FIG. 18B, when pressed in one direction, the pressingmember 22 is brought into contact with the resistive film pattern 74. Todetect this contact position (i.e., the pressing direction), apredetermined voltage is applied between the pair of extractionelectrodes 74 ₁ and 74 ₃ via a resistor for voltage division, as theswitches SW1 and SW2 are connected to contact points x in the circuitdiagram of FIG. 20. More specifically, the voltage Vcc is applied to theextraction electrode 74 ₁ via a resistor R1 for voltage division, andthe extraction electrode 74 ₃ is grounded via a resistor R2 for voltagedivision. At this point, the potential of the electrode pattern 73 isobtained through the conductive pressure-sensitive member (the pressingmember) 22. This potential serves as the pressing point informationrelative to the straight line (hereinafter referred to as “X direction”)connecting the extraction electrodes 74 ₂ and 74 ₄ when the pressingmember 22 is in contact with the resistive film pattern 74. Since thepressing member 22 is made of a conductive pressure-sensitive material,the resistive film pattern 74 and the electrode pattern 73 are connectedto each other with a resistor. The value of this resistor becomessmaller, as the pressing force of the conductive pressure-sensitivemember becomes greater. Accordingly, the potential of the electrodepattern 73 also reflects the pressing force in a case where the switchSW1 is connected to a contact point z and the SW2 is connected to thecontact point x in the circuit diagram of FIG. 20. Especially, as longas the resistance value of the conductive pressure-sensitive member isgreater than the resistance value of the resistive film pattern 74, thevariation of the resistance value of the resistive film pattern 74 withpressing points (i.e., the variation of the resistance value of theresistive film pattern 74 with the pressing points ranging from thecontact point with the pressing member 22 to the extraction electrode 74₃ in this example) can be ignored, and the pressing force detection canbe performed accurately. Because of these facts, this embodiment issuitable for a structure having a resistive film pattern of a smalldiameter.

[0104] A predetermined voltage is next applied between the other pair ofextraction electrodes 74 ₂ and 74 ₄ via a resistor for voltage division,and the potential of the electrode pattern 73 is obtained. Thispotential serves as the pressing position information relative to thestraight line (hereinafter referred to as “Y direction”) connecting theextraction electrodes 74 ₁ and 74 ₃, and also reflects pressing force.

[0105] In this manner, the position information relative to the Xdirection and the Y direction is obtained to detect pressing directionsin the angle range of 360 degrees as well as pressing forces. Inaccordance with this embodiment, prior to the detecting operation, thepotentials of the extraction electrodes 74 ₂ and 74 ₄ in a case where apredetermined voltage is applied between the extraction electrodes 74 ₁and 74 ₃, and the potentials of the extraction electrodes 74 ₁ and 74 ₃in a case where a predetermined voltage is applied between theextraction electrodes 74 ₂ and 74 ₄, are stored as the potential valuesat the positions of the respective electrodes, and are used forcalibration. By doing so, more accurate pressing direction detection canbe realized.

[0106] If the pressing member 22 is made of a conductive material,instead of a conductive pressure-sensitive material, only pressingdirections can be detected.

[0107] (Ninth Embodiment)

[0108]FIG. 21 shows a pattern of a pressing direction sensor accordingto a ninth embodiment of the present invention. In this figure, the samecomponents as in the pattern shown in FIG. 19 are denoted by the samereference numerals as in FIG. 19. The pressing direction sensoraccording to the ninth embodiments is characterized by a ring-likeelectrode pattern 76 added to the pattern shown in FIG. 19, and detectsa pressing force by detecting the resistance value of the pressingmember 22 between the electrode patterns 73 and 76 at the time ofpressing.

[0109] To detect a pressing force, the electrode pattern 76 is added tothe pattern shown in FIG. 19. This electrode pattern 76 has a completering shape, and is interposed between the resistive film pattern 74 andthe electrode pattern 73. The electrode pattern 76 has an extractionelectrode 76 ₁ that extends onto the bottom surface of the printedwiring board 10 via a through hole formed in the printed wiring board10.

[0110] The pressing direction detection is performed in the same manneras in the eighth embodiment. The pressing force detection is performedin the same manner as in the structure shown in FIG. 6B. A voltage Vccis applied to the electrode pattern 76 via a resistor for voltagedivision, so that the pressing force can be detected from the detectionvoltage that appears on the extraction electrode 76 ₁ when the pressingmember 22 is pressed. In this embodiment, it is not necessary to makethe resistance value of the resistive film pattern 74 smaller than theresistance value of the conductive pressure-sensitive member as in theeighth embodiment, because the electrode pattern 76 is provided fordetecting pressing forces. Accordingly, this embodiment is applicable toa structure having a resistive film pattern of a large diameter.

[0111] In this manner, the pressing direction sensor according to theninth embodiment can detect pressing directions in the angle range of360 degrees, as well as pressing forces. Furthermore, this pressingdirection sensor has a small number of components, and is smaller andthinner than the conventional sensors.

[0112] (Tenth Embodiment)

[0113]FIG. 22 is a sectional view of a pressing direction sensoraccording to a tenth embodiment of the present invention. In thisfigure, the same components as in the foregoing embodiments are denotedby the same reference numerals as in the foregoing embodiments. Thisembodiment is characterized by detecting pressing directions andpressing forces without a resistive film pattern.

[0114] As shown in FIG. 22, this pressing direction sensor includes theprinted wiring board 10 and a pressing member (an operation unit) 22A.The pressing member 22A is made of a conductive pressure-sensitivematerial that has elasticity and a resistance value variable withpressures applied, such as conductive pressure-sensitive rubber. Thispressing member 22A differs from the pressing member 22 shown in FIGS.4A and 4B in that two protrusions (or three protrusions in the sectionalview) facing the printed wiring board 10 are in contact with a patternformed on the printed wiring board 10 in the stationary state.

[0115]FIG. 23 shows the pattern formed on the printed wiring board 10.This pattern includes four electrode patterns 81 ₁, 81 ₂, 82 ₁, and 82₂, and an electrode pattern 13. The four electrode patterns 81 ₁, 81 ₂,82 ₁, and 82 ₂ are shaped like a ring-like electrode that has been cutoff by a predetermined length at regular intervals. In other words, thefour electrode patterns 81 ₁, 81 ₂, 82 ₁, and 82 ₂ are arranged in afan-like form at regular intervals of a predetermined angle. Theelectrode pattern 13 is positioned concentrically with the fourelectrode patterns 81 ₁, 81 ₂, 82 ₁, and 82 ₂. Being located at thecenter of the ring-like arrangement of the electrode patterns 81 ₁, 81₂, 82 ₁, and 82 ₂, the electrode 13 will be hereinafter referred to asthe “center electrode pattern”.

[0116] The electrode pattern 81 ₁ is paired with the electrode pattern81 ₂, while the electrode pattern 82 ₁ is paired with the electrodepattern 82 ₂. A voltage Vcc is applied to the electrode pattern 81 ₁,and the electrode pattern 81 ₂ is grounded. Likewise, a voltage Vcc isapplied to the electrode pattern 82 ₁, and the electrode pattern 82 ₂ isgrounded, though not shown in FIG. 23.

[0117]FIG. 24 shows a circuit formed between the electrode patterns 81 ₁and 81 ₂. In this figure, a resistor R11 represents the resistance ofthe conductive pressing member 22A connecting the electrode pattern 81 ₁to the center electrode pattern 13, and a resistor R12 represents theresistance of the pressing member 22A connecting the center electrodepattern 13 to the pressing member 22A. A similar circuit is formedbetween the electrode patterns 82 ₁ and 82 ₂. In the stationary stateshown in FIG. 22, the resistor R11 is equal to the resistor R12, and thedetection voltage Vout of the center electrode pattern 13 is Vcc/2accordingly. Here, a voltage is applied only to Vcc. When the pressingmember 22A is pressed in any one direction, the pressed point iscompressed, and the resistance value at the pressed point decreases. Asa result, the detection voltage Vout changes. Since the detectionvoltage Vout varies with pressing forces, the pressing force can bedetected from the detection voltage Vout. Likewise, when the voltage Vccis applied to the electrode pattern 82 ₁, the pressing force can bedetected from the detection voltage Vout.

[0118] To detect the pressing direction, the voltage Vcc is firstapplied only to the electrode pattern 81 ₁ so as to obtain the detectionvoltage Vout. The obtained detection voltage Vout indicates the pressedpoint located on the straight line connecting the electrode patterns 81₁ and 81 ₂. The voltage Vcc is next applied to the electrode pattern 82₁ so as to obtain the detection voltage Vout. The obtained detectionvoltage Vout indicates the pressed point located on the straight lineconnecting the electrode patterns 82 ₁ and 82 ₂. The pressing directioncan be detected from the two pressed points determined in this manner.

[0119] As described above, in accordance with the tenth embodiment ofthe present invention, a small and thin pressing direction sensor thatcan detect pressing directions and pressing forces can be realized witha very simple structure employing no resistive film patterns.

[0120] (Eleventh Embodiment)

[0121]FIG. 25 is a sectional view of a pressing direction sensoraccording to an eleventh embodiment of the present invention. In thisfigure, the same components as in the foregoing embodiments are denotedby the same reference numerals as in the foregoing embodiments. FIG. 26shows an electrode pattern formed on the printed wiring board 10.

[0122] The pressing direction sensor of this embodiment detects pressingdirections and pressing forces, having the same principles as the tenthembodiment. This pressing direction sensor further includes the tactileswitch 34 described with reference to FIG. 7. Also, a pressing member(an operation unit) 92 is employed instead of the pressing member 22Ashown in FIG. 22, and a conductive pressure-sensitive rubber sheet 85 isemployed in this pressing direction sensor. Further, a ring-like centerelectrode pattern 84 is employed instead of the round center electrodepattern 13 shown in FIG. 22.

[0123] As shown in FIG. 25, the ring-like center electrode pattern 84surrounds the tactile switch 34. Also, the center electrode pattern 84is arranged concentrically with the four electrode patterns 81 ₁, 81 ₂,82 ₁, and 82 ₂. The ring-like conductive pressure-sensitive rubber sheet85 having the same structure as shown in FIG. 9 is placed on theelectrode patterns and the tactile switch 34. In the stationary state,the conductive pressure-sensitive rubber sheet 85 is in contact with twoprotrusions formed on the bottom surface of the pressing member 92. Alsoin the stationary state, the conductive pressure-sensitive rubber sheet85 is in contact with the electrode patterns 81 ₁, 81 ₂, 82 ₁, and 82 ₂,as well as the elastic member 34 b of the tactile switch 34.

[0124]FIG. 27 shows the detection circuit according to this embodiment.A resistor R11 represents the resistance of the conductivepressure-sensitive rubber sheet 85 between the electrode pattern 82 ₁and the center electrode pattern 84, and a resistor R12 represents theresistance of the conductive pressure-sensitive rubber sheet 85 betweenthe center electrode pattern 84 and the electrode pattern 82 ₂.Likewise, a resistor R13 represents the resistance of the conductivepressure-sensitive rubber sheet 85 between the electrode pattern 81 ₁and the center electrode pattern 84, and a resistor R14 represents theresistance of the conductive pressure-sensitive rubber sheet 85 betweenthe center electrode pattern 84 and the electrode pattern 81 ₂. Pressingdirections and pressing forces can be detected from detection voltagesVx and Vy. As the pressing member 92 is pressed vertically downward, thetactile switch 34 is turned ON.

[0125] As described above, the pressing direction sensor according tothe eleventh embodiment can detect pressing directions in the anglerange of 360 degrees, as well as pressing forces. This pressingdirection sensor can further detect the ON/OFF state corresponding tothe vertical-direction operation. Furthermore, this pressing directionsensor has a small number of components, and accordingly is smaller andthinner than the conventional sensors.

[0126] (Twelfth Embodiment)

[0127]FIG. 28 is a sectional view of a pressing direction sensoraccording to a twelfth embodiment of the present invention. FIG. 29illustrates a membrane sheet employed in the pressing direction sensorshown in FIG. 28. FIG. 30 is a perspective view of the outlook of thepressing direction sensor according to the twelfth embodiment. Thispressing direction sensor can detect pressing directions and pressingforces. This embodiment is the same as the first through ninthembodiments in that a resistive film pattern is employed. Thisembodiment is also the same as the tenth and eleventh embodiments inthat an x-coordinate position and a y-coordinate position are detected.

[0128] As shown in FIG. 28, the pressing member 92 is placed over theprinted wiring board 10. In this embodiment, the pressing member 92 doesnot need to have conductivity. A step portion is formed inside thepressing member 92, and the edge portion of the membrane sheet 93 shownin FIG. 29 is engaged with and supported by the step portion. Themembrane sheet 93 consists of a round part and a rectangular protrudingpart. A resistive film pattern 94 formed by carbon printing or the like,and electrode patterns 95 ₁, 95 ₂, 96 ₁, and 96 ₂, are formed on theround part of the membrane sheet 93. The resistive film pattern 94 has around shape. The electrode patterns 95 ₁ and 95 ₂ face each other andform a pair. Likewise, the electrode patterns 96 ₁ and 96 ₂ face eachother and form a pair. The electrode patterns 95 ₁, 95 ₂, 96 ₁, and 96 ₂are formed on the resistive film pattern 94, and are electricallyconnected. The extraction electrodes of the electrode patterns 95 ₁, 95₂, 96 ₁, and 96 ₂ are formed on the protruding part of the membranesheet 93, and the end portion 99 of the protruding part is a connectingportion for connection with the outside.

[0129] A center electrode pattern 97 is formed on the upper surface ofthe printed wiring board 10. This center electrode pattern 97 is around-shaped pattern that is smaller than the round-shaped resistivefilm pattern 94 by the width of each of the electrode patterns 95 ₁, 95₂, 96 ₁, and 96 ₂.

[0130] In the stationary state, the resistive film pattern 94 is not incontact with the center electrode pattern 97. When the pressing member92 is pressed in any one direction, the resistive film pattern 94 isbrought into contact with the center electrode pattern 97. The pressingdirection and pressing force detections are performed by applying avoltage to the two pairs of electrode patterns. More specifically, avoltage Vcc is first applied between the electrode patterns 95 ₁ and 95₂ so as to detect the x-coordinate value of the pressed point (or thepressing direction). At this point, the voltage value represents thepressing force. The same voltage Vcc is next applied to the electrodepatterns 96 ₁ and 96 ₂ so as to detect the y-coordinate value. In thismanner, the pressing direction and the pressing force of the pressingmember 92 can be detected.

[0131] The voltage applying order may be controlled by a centralprocessing unit described later. Also, the center electrode pattern 97may be formed on the membrane sheet 93 instead of the printed wiringboard 10, and the resistive film pattern 94 and the electrode patterns95 ₁, 95 ₂, 96 ₁, and 96 ₂, may be formed on the printed wiring board 10instead of the membrane sheet 93. It is also possible to form theresistive film pattern 94 on the printed wiring board 10, and to formonly electrode patterns on the membrane sheet 93 by Ag printing or thelike.

[0132] (Thirteenth Embodiment)

[0133]FIG. 31 is a sectional view of a pressing direction sensoraccording to a thirteenth embodiment of the present invention. In thisfigure, the same components as in the foregoing embodiments are denotedby the same reference numerals as in the foregoing embodiments. Thisembodiment is to detect pressing directions and pressing forces by thesame principles as the tenth and eleventh embodiments, and accordinglyis a modification of the tenth and eleventh embodiments.

[0134] The center electrode 13 and the four electrode patterns 81 ₁, 81₂, 82 ₁, and 82 ₂, are arranged on the printed wiring board 10 in thesame manner as in FIG. 23. In FIG. 31, only two of the electrodepatterns 82 ₁ and 82 ₂ can be seen. A round-shaped conductivepressure-sensitive rubber sheet 103 is placed over the center electrodepattern 13 and the four electrode patterns 81 ₁, 81 ₂, 82 ₁, and 82 ₂.In the stationary state, this conductive pressure-sensitive rubber sheet103 is in contact with the center electrode pattern 13 and the fourelectrode patterns 81 ₁, 81 ₂, 82 ₁, and 82 ₂. A metal plate 104 isplaced over the conductive pressure-sensitive rubber sheet 103. Thismetal plate 104 has two ring-like protrusions (three protrusions in thesectional view). The outer ring-like protrusion may be a complete ring,or four separate portions corresponding to the four electrode patterns81 ₁, 81 ₂, 82 ₁, and 82 ₂. The metal plate 104 and the conductivepressure-sensitive rubber sheet 103 are accommodated in a concaveportion formed on the bottom surface of a pressing member 102.

[0135] When the pressing member 102 is pressed in any one direction, thebottom surface of the pressing member 102 presses the metal plate 104.The concave portion of the metal plate 104 then presses the conductivepressure-sensitive rubber sheet 103. As a result, the conductivepressure-sensitive rubber sheet is compressed at the pressed point, andthe resistance value thereof decreases. Under these conditions, thecoordinates of the pressed point in the x-axis direction and the y-axisdirection are detected in the above described manner, so as to detectthe pressing direction and the pressing force.

[0136] It should be noted that the combination of the pressing member102 and the metal plate 104 is not limited to this embodiment, but isapplicable to any of the foregoing embodiments.

[0137] Also, in any of the foregoing embodiments, the pressing membermay be formed so as to realize the relationship between the pressedlength and the pressing force as shown in FIG. 32. By forming thepressing member in this manner, a clicking feeling can be felt when thepressing member is pressed, and thus the pressing member, which servesas the switch for pressing operations perpendicular to the wiring board,can provide a pleasant feeling in handling.

[0138] (Other Embodiments)

[0139]FIG. 33 illustrates an example of an electronic device having apressing direction sensor of the present invention on a printed wiringboard. More specifically, this electronic device is provided with apressing direction sensor 110, a signal processing circuit 112, and aconnector 113 for outer connection, all of which are placed on a printedwiring board 111. The pressing direction sensor 110 is a pressingdirection sensor according to the twelfth embodiment of the presentinvention, but of course may be a pressing direction sensor according toany of the other foregoing embodiments.

[0140]FIG. 34 illustrates an electronic device according to yet anotherembodiment of the present invention. This electronic device may be usedfor a pointing device, a printed wiring board, a remote control device,and a portable telephone. In the structure shown in FIG. 34, a pressingdirection sensor pattern and a plurality of switch contact patterns areformed on a printed wiring board. An operation unit (a pressing member)114 for detecting pressing directions, and a plurality of switch rubbercontacts that are integrally molded out of an elastomeric material, areplaced over those patterns, and are covered and pressed with a moldcover.

[0141]FIG. 35 is a block diagram illustrating an example of the innerstructure of the above electronic device. This structure includes apressing direction sensor 121, an analog-digital converter 122, and acentral processing unit 123. The central processing unit 123 includes astorage unit 125, an arithmetic operation unit 124, a clock unit 126that generates clocks, and an interface unit 127. The pressing directionsensor 121 is equivalent to the pressing direction sensor 110 shown inFIG. 33, for example, and the analog-digital converter 122 and thecentral processing unit 123 are equivalent to the signal processingcircuit 112. The connector 113 for outer connection shown in FIG. 33 isto be connected to the interface unit 127 of the central processing unit123 shown in FIG. 35.

[0142] The central processing unit 123 controls the pressing directionsensor 121, and processes the output voltage of the pressing directionsensor 121.

[0143] As described so far, in accordance with the present invention, asmall and thin pressing direction sensor that can continually detectpressing directions in the angle range of 360 degrees. The presentinvention also provides a pressing direction sensor that can detectpressing forces as well as pressing directions. Furthermore, the presentinvention can provide various electronic devices that employ the abovepressing direction sensor.

[0144] Finally, several aspects of the invention are summarized belowfor reference.

[0145] According to an aspect, there is provided a pressing directionsensor comprising: a ring-like resistive film pattern; a first electrodepattern; and a conductive member that is electrically connected to theresistive film pattern and the first electrode pattern when pressed, thepotential of the resistive film pattern at the point of contact of theconductive member with the resistive film pattern being outputted fromthe first electrode pattern, so as to detect a pressing direction. Thepotential of the resistive film pattern at the point at which theconductive member contacts the resistive film pattern depends on theresistance value of the resistive film pattern available at the point.Thus, the pressing direction can be detected by the potential of thepoint via the first electrode pattern.

[0146] The pressing direction sensor may be configured so that itfurther includes a second electrode pattern; the conductive member beinga conductive pressure-sensitive member that has a resistance valuevariable with pressures applied; the conductive member being broughtinto contact with the first and second electrode patterns when pressed;and a signal generated from the contact of the pressed conductive memberwith the first and second electrode patterns being outputted so as todetect a pressing force. The conductive pressure-sensitive member has aresistance value that depends on pressure. Thus, the voltage developingacross the first and second electrode patterns reflects the pressure. Itis therefore possible to detect the pressure from the voltage developingacross the first and second electrode patterns.

[0147] The pressing direction sensor may be configured so that: theresistive film pattern has a notch formed by cutting a part off aring-like pattern; and a voltage is applied via two facing ends formedby the notch of the resistive film pattern. Current flows in theresistive film pattern from one of the two facing ends to the other.Under this condition, when the conductive member is pressed, contact ismade between the ring-like resistive film pattern and the firstelectrode pattern. The pressing direction can be detected by outputtingthe potential of the point at which the conductive member contacts theresistive film pattern via the first electrode pattern.

[0148] The pressing direction sensor may be configured so that: theresistive film pattern has a ring-like shape; and extraction electrodesto be connected to the resistive film pattern are arranged around theresistive film pattern at regular intervals of 90 degrees. A voltage isapplied across the facing extraction electrodes. This results in currentthat flows from one of the facing extraction electrodes to the other viathe resistive film pattern. Under this condition, when the conductivemember contacts the resistive film pattern, the potential of the firstelectrode results from the resistance value of the resistive filmpattern available at the contact point.

[0149] The pressing direction sensor may be configured so that the firstelectrode pattern is arranged concentrically with the resistive filmpattern.

[0150] The pressing direction sensor may be configured so that the firstelectrode pattern has either a round shape or a ring-like shape arrangedconcentrically with the resistive film pattern.

[0151] The pressing direction sensor may be configured so that: theresistive film pattern has a notch formed by cutting a part off aring-like pattern; and a separate electrode pattern is interposedbetween two facing ends formed by the notch. When the conductive membercontacts the separate electrode patterns, the facing ends of theresistive film pattern are connected via the conductive member. At thistime, the separate electrode pattern becomes a particular potential. Itis therefore possible to detect the potential of the separate electrodepattern so as to detect the direction of the location of the separateelectrode pattern.

[0152] The pressing direction sensor may be configured so that itfurther includes a substrate, the first electrode pattern and theresistive film pattern being formed on the substrate, and the conductivemember facing the substrate.

[0153] The pressing direction sensor may be configured, so that: theconductive member is interposed between the resistive film pattern andthe first electrode pattern; and an operation unit is further providedso as to bring the resistive film pattern into contact with the firstelectrode pattern via the conductive member when the operation unit ispressed.

[0154] The pressing direction sensor may be configured so that itfurther comprises a sheet-like member that supports the resistive filmpattern and the first electrode pattern, the conductive member beingsandwiched by the sheet-like member, and the operation unit being placedat one side of the sheet-like member.

[0155] The pressing direction sensor may be configured so that itfurther includes: a sheet-like member that supports the resistive filmpattern, the first electrode pattern, and the second electrode pattern;and an operation unit that serves to bring the resistive film pattern,the first electrode pattern, and the second electrode pattern intocontact with one another, with the conductive member being sandwiched bythe sheet-like member.

[0156] The pressing direction sensor may be configured so that itfurther includes a switch that is turned on when the conductive memberis pressed vertically downward. It is therefore possible to realize thepressing direction sensor equipped with the switch function in additionto detection of the pressing direction and/or pressure.

[0157] The pressing direction sensor may be configured so that theconductive member has a resistance value variable with pressuresapplied. The pressure can be sensed by utilizing change of theresistance value.

[0158] The pressing direction sensor may be configured so that theconductive member includes a ring-like conductive pressure-sensitiverubber that has a resistance value variable with pressures applied. Thering-line conductive pressure-sensitive rubber is one example of theconductive member. The pressure can be sensed by utilizing change of theresistance value.

[0159] The pressing direction sensor may be configured so that itfurther includes an operation unit that presses the conductive member.

[0160] The pressing direction sensor may be configured so that itfurther includes a circuit for applying a voltage to the resistive filmpattern after a signal is outputted from the second electrode pattern.The voltage is applied to the resistive film pattern after pressing. Itis therefore possible to prevent current from being consumed wastefully.

[0161] The pressing direction sensor may be configured so that: anextraction electrode is provided at a predetermined position withrespect to the resistive film pattern; and the potential of theextraction electrode is set as a reference potential for detecting apressing direction. This improves the detection accuracy.

[0162] The pressing direction sensor may be configured so that thepotential of the second electrode pattern is compared with apredetermined threshold value, so as to determine whether the conductivemember has been pressed vertically downward. It is thus possible toachieve the pressing direction sensor equipped with the switch functionin addition to detection of the pressing direction and/or pressure.

[0163] According to another aspect of the present invention, there isprovided a pressing direction sensor comprising: a center electrodepattern; a plurality of pairs of electrode patterns, the electrodepatterns of each pair facing each other, with the center electrodepattern existing therebetween; and a conductive pressure-sensitivemember that is in contact with the plurality of pairs of electrodepatterns in the stationary state, and has a resistance value variablewith pressures applied, a pressing direction and a pressing force of theconductive pressure-sensitive member being detected from a signalobtained from the center electrode pattern when the conductivepressure-sensitive member is pressed. This sensor can sense the pressingdirection and pressure without the resistive film pattern. When pressed,the potential of the center electrode pattern changes from the potentialavailable in the stationary state. The pressure can be detected by thepotential change. Voltages are applied to the respective pairs ofelectrode patterns. Thus, the center electrode pattern becomes at thepotential that reflects the coordinates position of the pressing pointon the lines connecting the pairs of electrode patterns. Thus, theposition of the pressing point, namely, the pressing direction can beobtained from the potentials of the center electrode patterns obtainedfor the respective pairs.

[0164] The pressing direction sensor may be configured so that: thecenter electrode pattern has a ring-like shape; and a switch that isturned on when the conductive member is pressed vertically downward isprovided at the center of the center electrode pattern. It is thuspossible to realize the sensor equipped with the switch function inaddition to detection of the pressing direction and/or pressure.

[0165] According to another aspect of the present invention, there isprovided a pressing direction sensor comprising: a round-shapedresistive film pattern; a plurality of pairs of electrode patterns thatare arranged along the outer circumference; and a center electrodepattern that is electrically connected to the resistive film patternthrough a pressing operation, a pressing direction and a pressing forcebeing detected from a signal obtained from the center electrode pattern.The center electrode pattern becomes at the potential that reflects thecoordinates position of the pressing point on the lines connecting thepairs of electrode patterns. Thus, the position of the pressing point,namely, the pressing direction can be obtained from the potentials ofthe center electrode patterns obtained for the respective pairs.According to yet another aspect of the present invention, there isprovided an electronic device comprising: a pressing direction sensor;and a signal processing circuit that processes an output signal from thepressing direction sensor, the pressing direction sensor is configuredas described above. Examples of this electronic device are pointingdevices, printed-circuit boards, remote controllers and portable phones.

[0166] Although a few preferred embodiments of the present inventionhave been shorn and described, it would be appreciated by those skilledin the art that changes may be made in these embodiments withoutdeparting from the principles and spirit of the invention, the scope ofwhich is defined in the claims and their equivalents.

What is claimed is:
 1. A pressing direction sensor comprising: aring-like resistive film pattern; a first electrode pattern; and aconductive member that is electrically connected to the resistive filmpattern and the first electrode pattern when pressed, the potential ofthe resistive film pattern at the point of contact of the conductivemember with the resistive film pattern being outputted from the firstelectrode pattern, so as to detect a pressing direction.
 2. The pressingdirection sensor as claimed in claim 1, further comprising a secondelectrode pattern, the conductive member being a conductivepressure-sensitive member that has a resistance value variable withpressures applied, the conductive member being brought into contact withthe first and second electrode patterns when pressed, and a signalgenerated from the contact of the pressed conductive member with thefirst and second electrode patterns being outputted so as to detect apressing force.
 3. The pressing direction sensor as claimed in claim 1,wherein: the resistive film pattern has a notch formed by cutting a partoff a ring-like pattern; and a voltage is applied via two facing endsformed by the notch of the resistive film pattern.
 4. The pressingdirection sensor as claimed in claim 1, wherein: the resistive filmpattern has a ring-like shape; and extraction electrodes to be connectedto the resistive film pattern are arranged around the resistive filmpattern at regular intervals of 90 degrees.
 5. The pressing directionsensor as claimed in claim 1, wherein the first electrode pattern isarranged concentrically with the resistive film pattern.
 6. The pressingdirection sensor as claimed in claim 1, wherein the first electrodepattern has either a round shape or a ring-like shape arrangedconcentrically with the resistive film pattern.
 7. The pressingdirection sensor as claimed in claim 1, wherein: the resistive filmpattern has a notch formed by cutting a part off a ring-like pattern;and a separate electrode pattern is interposed between two facing endsformed by the notch.
 8. The pressing direction sensor as claimed inclaim 7, wherein the potential of the separate electrode pattern isdetected so as to detect the direction of the location of the separateelectrode pattern.
 9. The pressing direction sensor as claimed in claim1, further comprising a substrate, the first electrode pattern and theresistive film pattern being formed on the substrate, and the conductivemember facing the substrate.
 10. The pressing direction sensor asclaimed in claim 1, wherein: the conductive member is interposed betweenthe resistive film pattern and the first electrode pattern; and anoperation unit is further provided so as to bring the resistive filmpattern into contact with the first electrode pattern via the conductivemember when the operation unit is pressed.
 11. The pressing directionsensor as claimed in claim 10, further comprising a sheet-like memberthat supports the resistive film pattern and the first electrodepattern, the conductive member being sandwiched by the sheet-likemember, and the operation unit being placed at one side of thesheet-like member.
 12. The pressing direction sensor as claimed in claim2, further comprising: a sheet-like member that supports the resistivefilm pattern, the first electrode pattern, and the second electrodepattern; and an operation unit that serves to bring the resistive filmpattern, the first electrode pattern, and the second electrode patterninto contact with one another, with the conductive member beingsandwiched by the sheet-like member.
 13. The pressing direction sensoras claimed in claim 1, further comprising a switch that is turned onwhen the conductive member is pressed vertically downward.
 14. Thepressing direction sensor as claimed in claim 1, wherein the conductivemember has a resistance value variable with pressures applied.
 15. Thepressing direction sensor as claimed in claim 1, wherein the conductivemember includes a ring-like conductive pressure-sensitive rubber thathas a resistance value variable with pressures applied.
 16. The pressingdirection sensor as claimed in claim 1, further comprising an operationunit that presses the conductive member.
 17. The pressing directionsensor as claimed in claim 2, further comprising a circuit for applyinga voltage to the resistive film pattern after a signal is outputted fromthe second electrode pattern.
 18. The pressing direction sensor asclaimed in claim 1, wherein: an extraction electrode is provided at apredetermined position with respect to the resistive film pattern; andthe potential of the extraction electrode is set as a referencepotential for detecting a pressing direction.
 19. The pressing directionsensor as claimed in claim 2, wherein the potential of the secondelectrode pattern is compared with a predetermined threshold value, soas to determine whether the conductive member has been pressedvertically downward.
 20. A pressing direction sensor comprising: acenter electrode pattern; a plurality of pairs of electrode patterns,the electrode patterns of each pair facing each other, with the centerelectrode pattern existing therebetween; and a conductivepressure-sensitive member that is in contact with the plurality of pairsof electrode patterns in the stationary state, and has a resistancevalue variable with pressures applied, a pressing direction and apressing force of the conductive pressure-sensitive member beingdetected from a signal obtained from the center electrode pattern whenthe conductive pressure-sensitive member is pressed.
 21. The pressingdirection sensor as claimed in claim 20, wherein: the center electrodepattern has a ring-like shape; and a switch that is turned on when theconductive member is pressed vertically downward is provided at thecenter of the center electrode pattern.
 22. The pressing directionsensor as claimed in claim 20, wherein a voltage is alternately appliedto the plurality of pairs of electrode patterns, so as to detect apressing direction and a pressing force of the conductivepressure-sensitive member.
 23. The pressing direction sensor as claimedin claim 20, wherein: the conductive pressure-sensitive member is asheet-like member; and an operation unit is further provided so as topress the sheet-like conductive pressure-sensitive member.
 24. Thepressing direction sensor as claimed in claim 20, wherein: theconductive pressure-sensitive member is a sheet-like member; and aconductive plate and an operation unit are further provided so as topress the sheet-like conductive pressure-sensitive member, the operationunit being placed over the conductive plate.
 25. A pressing directionsensor comprising: a round-shaped resistive film pattern; a plurality ofpairs of electrode patterns that are arranged along the outercircumference; and a center electrode pattern that is electricallyconnected to the resistive film pattern through a pressing operation, apressing direction and a pressing force being detected from a signalobtained from the center electrode pattern.
 26. An electronic devicecomprising: a pressing direction sensor; and a signal processing circuitthat processes an output signal from the pressing direction sensor, thepressing direction sensor comprising: a ring-like resistive filmpattern; a first electrode pattern; and a conductive member that iselectrically connected to the resistive film pattern and the firstelectrode pattern when pressed, the potential of the resistive filmpattern at the point of contact of the conductive member with theresistive film pattern being outputted from the first electrode pattern,so as to detect a pressing direction.